Exhibit 10-2 the Figure Below Shows a Graph of Angular $- \frac { \pi } { 90 }$

Multiple Choice

Exhibit 10-2 The figure below shows a graph of angular velocity versus time for a man bicycling around a circular track. Use this exhibit to answer the following question(s) .
-Refer to Exhibit 10-2.What is his average angular acceleration,in rad/s²,in the period from t = 6 min to t = 8 min?

A) 0
B) $- \frac { \pi } { 90 }$
C) $- \frac { \pi } { 30 }$
D) $+ \frac { \pi } { 30 }$
E) $+ \frac { \pi } { 90 }$